If positive, int_like or int-convertible arguments are provided,
randn generates an array of shape (d1,...,dn), filled
with random floats sampled from a univariate “normal” (Gaussian)
distribution of mean 0 and variance 1 (if any of the are
floats, they are first converted to integers by truncation). A single
float randomly sampled from the distribution is returned if no
argument is provided.

This is a convenience function. If you want an interface that takes a
tuple as the first argument, use numpy.random.standard_normal instead.

Parameters:

d1, ..., dn : n ints, optional

The dimensions of the returned array, should be all positive.

Returns:

Z : ndarray or float

A (d1,...,dn)-shaped array of floating-point samples from
the standard normal distribution, or a single such float if
no parameters were supplied.